Scourge of the Throne

Flying, dethrone (Whenever this creature attacks
the player with the most life or tied for most life, put a
+1/+1 counter on it.)
Whenever Scourge of the Throne attacks for the
first time each turn, if it's attacking the player
with the most life or tied to for the most life,
untap all attacking creatures. After this phase,
there is an additional combat phase.